conditions. Under altering conditions, this lack would be fatal. But this
would be the fatality of some species or form in particular, not of species
or forms generally, which, for the most part, may and do vary sufficiently,
and in varying survive, seemingly none the worse, but rather the better,
for their long tenure of life.

The opposite idea, however, is maintained by M. Naudin,[XII-1] in a
detailed exposition of his own views of evolution, which differ widely from
those of Darwin in most respects, and notably in excluding that which, in
our day, gives to the subject its first claim to scientific (as
distinguished from purely speculative) attention; namely, natural
selection. Instead of the causes or operations collectively personified
under this term, and which are capable of exact or probable appreciation,
M. Naudin invokes "the two principles of rhythm and of the decrease of
forces in Nature." He is a thorough evolutionist, starting from essentially
the same point with Darwin; for he conceives of all the forms or species of
animals and plants "comme tire tout entier d'un protoplasma primordial,
uniform, instable, eminemment plastique." Also in "l'integration croissante
de la force evolutive a mesure qu'elle se partage dans les formes produites,
et la decroissance proportionelle de la plasticite de ces formes a mesure
qu'elles s'eloignent davantage de leur origine, et qu'elles sont mieux
arretees." As they get older, they gain in fixity through the operation of
the fundamental law of inheritance; but the species, like the individual,
loses plasticity and vital force. To continue in the language of the
original:


"C'est dire qu'il y a eu, pour l'ensemble du monde organique, une periode
de formation ou tout etait changeant et mobile, une phase analogue a la vie
embryonnaire et a la jeunesse de chaque etre particulier; et qu'a cet age